1. Field of the Invention
This invention relates to apparatus for horizontally conveying glass plates standing on edge, comprising a bottom edge supporting conveyor having a plane of conveyance which is horizontal or is slightly inclined from the horizontal, and a supporting wall, which is disposed above said conveyor and serves to laterally support glass plates standing on said conveyor, which supporting wall is slightly inclined from the vertical and includes a right angle or an angle of approximately 90.degree. with the plane of conveyance, wherein a fan for producing an air cushion is provided on the planar front surface of the supporting wall and on its delivery side communicates through one or more ducts with one or more upwardly directed slot-shaped exit openings, which extends or extend along the lower edge of the supporting wall.
2. Description of the Prior Art
Apparatus of the kind described hereinbefore are known in the art, e.g., from DE 33 08 079 C2. They are used, e.g., in production lines for making insulating glass consisting of two or more glass plates. Such production lines consist, as a rule, of a glass plate washing machine, which is succeeded by a checking station for checking whether the glass plates are clean, by a frame-applying station for applying spacer frames to individual glass plates, by an assembling station, in which the glass plates are superimposed, with a spacer interposed, and are adhesively joined, optionally by a press for pressing plates which have thus been assembled, also optionally by a sealing station, in which a gap formed at the edge of the insulating glass pane is sealed by means of a sealant consisting of a viscous paste, and finally by a taking station, in which the complete insulating glass panes are taken from the production line. As the glass plates move through all said stations, they stand on edge on a bottom edge supporting conveyor, which in most cases consists of a horizontal series of driven rollers having horizontal or approximately horizontal axes, or of a horizontally extending, supported endless conveyor belt, or of a horizontally extending conveyor chain provided with supports for the glass plates standing on edge, or of a pair of conveyor chains for engaging and gripping the individual glass plates of the insulating glass pane at the lower edge of said plates on both sides and for optionally supporting them at their lower edges by suitable supports. In the present description the horizontal or approximately horizontal plane on which the individual glass plates or insulating glass panes stand on edge is described as a plane of conveyance. As the glass plates standing on edge pass through said stations, the glass plates are slightly inclined from the vertical, in most cases at an angle of 5 to 7 degrees, and lean against a supporting structure so that they cannot fall down. Intermediate conveyor sections and retaining conveyor sections are disposed between said stations and each of said conveyor sections is also provided with a bottom edge supporting conveyor and with a lateral support. The supporting structure is often an air cushion wall.
The air cushion walls usually consist of a coated board of wood, which is formed with air exit openings, which are distributed over the forward surface of the board and regularly spaced apart and consist of through bores which extend at right angles to said forward surface. In the known air cushion walls the rear side of the plate of wood is covered by a box, which together with the wooden board constitutes a closed housing, which via a supply duct receives air from a blower and delivers said air through the bores in the plate of wood so that a glass plate leaning against the board of wood will be slightly disengaged from said board and will cause an air cushion to be formed between the glass plate and the board so that the glass plate is laterally supported on the board without contacting it.
In that connection it is also known to provide in the board near its lower edge a linear series of air exit openings which are spaced a smaller distance apart than adjacent air exit openings in the remaining area of the board.
DE 33 08 079 C2 discloses an air cushion wall, which is not provided in its forward surface with air exit openings but in which a slot nozzle having upwardly facing exit orifices extends along the lower edge of the wall and through said orifices delivers air from the fan into the space between the supporting wall and a glass plate leaning against the wall.
Apparatus for conveying glass panes should be suitable for handling plates of all sizes used in practice. The sizes of the plates used in practice vary in a wide range, and the plates may have edge lengths from about 20 cm to about 3 m. In the operation of the previously known glass plate conveying apparatus comprising an air cushion wall it is difficult to ensure that large and heavy glass plates as well as small and lightweight glass plates will be conveyed with equal effectiveness and reliability. In those of the known apparatus in which the air cushion walls which are optimized for the conveyance of heavy plates, there is a risk that the air blasts directed against lightweight plates will be so strong so that such plates will be tilted from the supporting wall. On the other hand, in those of the known apparatus in which the air cushion wall is optimized for the conveyance of lightweight plates, there will be a risk that heavy plates will not be disengaged from the supporting wall but will move in contact with said wall.